Embodiments of the inventive concept relate generally to semiconductor memory devices. More particularly, embodiments of the inventive concept relate to floating gate type flash memory devices and related methods of manufacture and operation.
Flash memory devices can be roughly divided into two categories according to a type of charge storage element used in their memory cells. These categories include charge trap type flash memory devices, which use an insulation layer (e.g., a silicon nitride layer) as the charge storage element, and floating gate type flash memory devices, which use an electrically isolated conductive pattern (i.e., a floating gate) as the charge storage element.
Due to limits of current technology, floating gate type flash memory devices tend to have superior reliability than charge trap type flash memory devices. Accordingly, most commercialized flash memory devices are floating gate type flash memory devices. As technology progresses, however, charge type flash memory devices are expected to gain popularity. For instance, the 2009 edition of International Technology Roadmap for Semiconductors (ITRS) predicts that three-dimensional charge trap flash memory devices will be commercially adopted by 2014, replacing many floating gate type flash memory devices.
Notwithstanding these predictions, the development of charge trap flash memory devices remains uncertain, and future improvements could allow floating gate type flash memory devices to remain the dominant form of flash memory for years to come.